Method of producing a fluted cone mandrel



June 30, 1970 C. w. HYDER 7 METHOD OF PRODUCING A FLUTED CONE MANDREL Filed Aug. 28, 1950 fiharleswfiyder $314M awn/MW United States Patent 01 iice 3,517,587 METHOD OF PRODUCING A FLUTED CONE MANDREL Charles W. Hyder, Silver Spring, Md., assignor to the United States of America as represented by the Secretary of the Army Filed Aug. 28, 1950, Ser. No. 181,905 Int. Cl. B23c 1/16 US. Cl. 90-13 2 Claims The invention herein described and claimed may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a method of producing a toothed mandrel or punch and, more particularly, to a method of producing such a mandrel or punch having the form of an externally fluted cone.

In the production of liners for shaped charges for use with rotating or spinning projectiles, such as those fired from a rifled gun, it is desirable that the liners of the charges be fluted for the purpose of nullifying the otherwise deleterious effect of spinning upon the penetrating power of the jet formed by detonation of the charge.

The number, shape and offset of the flutes will depend upon several factors such as velocity or rate of spin of the projectile at impact, size and composition of charge, and others and is predetermined in well known ways, by formulae and/ or experiment.

It has been found that the simplest and least expensive way to produce these fluted liners in large quantities is by inserting a smooth conical shell of suitable metal, such as copper or aluminum, within a female die and then pressing the same by means of a punch or mandrel. As the male and female members utilized are subject to wear and frequent replacement, they must be capable of inexpensive and rapid production. Furthermore, it is highly desirable that the liners be extremely accurate, particularly as regards identity of the several flutes.

It is therefore the principal object of the invention to provide a method by which a male member, punch or mandrel of the type described, may be formed with a high degree of accuracy both as to absolute and relative dimensions of the successive flutes and spacing thereof.

Other objects and advantages will be obvious after a study of the following detailed description.

In the drawings:

FIG. 1 is a perspective view of a complete liner with sixteen flutes;

FIG. 2 is a perspective view of the fluted mandrel or male member;

FIG. 3 is a perspective view of the die or female member;

FIG. 4 is a perspective view of the master pattern used in practicing the invention;

FIG. 5 is an end elevation of the master pattern of FIG. 4;

FIG. =6 is a diagrammatic view showing the use of the master pattern to produce a flute of proportional dimensions, and

FIG. 7 is a view corresponding to FIG. 6, showing the use of the master pattern to produce a flute of greater depth than FIG. 6.

Referring in detail to the drawing, the numeral 1 identifies generally a mandrel or male member having a plurality of regularly-spaced flutes 2 each comprising a generally radially offset surface or portion 3, and a canted portion or surface 4 joiningthe radially outer edge of each oflset surface with the radially inwardedge of the next suceeding surface. A coaxial stem 5 is rigidly attached to the member 1 and forms means 3,517,587 Patented June 30, 1970 by which the mandrel may be mounted in a suitable press, not shown.

The die or female member is identified at 6, FIG. 3, and has its generally conical cavity formed with flutes corresponding in number, size and shape to the flutes upon the external surface of member 1. Thus the member 6 has sixteen flutes each comprising a radially offset surface 7 and a canted surface 8. In use, the member 6 is rigidly mounted upon the base or anvil of the press with its contral axis in alignment with the axis of member 1 and with each radial surface 7 circumferentially spaced from a corresponding surface 3 of member 1, by substantially the thickness of the material of the liner to be shaped. A smooth liner is then positioned in female member 6 and member 1 is forced downwardly to press the liner between members 1 and 6, into the completed form.

The foregoing is a typical press-punch operation and, per se, forms no part of my invention. As previously noted, it is extremely important in the firing of shaped charges from rifled guns, that the spin of projectile be compensated at the instant the charge is detonated in order to afford maximum penetration of the jet formed by the charge, that is, a penetration equal to a like charge when fired statically at optimum stand-off distance. Furthermore, it has been experimentally determined that one of the factors favorable to complete compensation is accurate precise fluting of the liners wherein the flutes are identical to a high degree of accuracy and uniformly spaced.

With this purpose in mind, my invention resides in a novel method of forming male member 1 with flutes which possess a high degree of accuracy and result in fluted cones of equal precision. In carrying out the method, I first form a master pattern, generally identified at 9, FIGS. 4 and 5 and comprising a web 10 having axially projecting mounting pintles 11 and 12. A pattern flange or surface 13 is shaped into a section of a cone of slightly greater angular extent than one complete flute of the liner to be produced, as indicated by the dash line 16 of FIG. 5. This surface is then patterned or shaped to form a canted surface 14 and offset sur face 15 corresponding to surfaces 2 and 3 of the com pleted punch. The master pattern thus produced is made to a predetermined enlarged scale, say 6 to 10* times the dimensions of the corresponding surfaces of the completed punch.

The master pattern or segment is then mounted in a standard milling machine equipped with a three-dimension pantograph attachment set so that all movements of the stylus as it follows the contour of the pattern or segment, are transmitted to the milling cutter in the exact reduced ratio equal to the enlargement factor of the pattern. Thus, if the pattern has been enlarged by a 6 X factor, the cutter will be moved one-sixth of the corresponding movement of the stylus.

In using the pattern in its normal position, the pattern and cone to be cut are mounted upon the work table with their center lines or axes in alignment. The work table is then adjusted until the center of the cutting tool is in exact alignment with the center line of the cone to be cut. After the pattern surface has been traversed by the stylus to cut a coresponding surface, to a reduced scale, upon the workpiece, the latter is rotated about its axis by means of the index head by which it is mounted upon the work table, through one-sixteenth of a circumference, or 22 /2, and again locked in position, after which the pattern is again traversed by the stylus. This procedure is repeated until the entire surface of the workpiece has been cut.

FIG. 5 illustrates a master cone segment or pattern placed vertically as it appears in the three-dimensional pantograph when the depth of the ridge formed in the workpiece is to be in direct scalar proportion to the corresponding dimension on the pattern.

FIG. 7 shows how, by tilting the pattern upon the sup port of the pantograph attachment to provide flutes of greater depth and less angular extent than that formed in the pattern.

The mandrel thus formed has the required number of flutes all of which are duplicates. Furthermore, due to its enlargement factor, the pattern can be cut or other wise formed with a high degree of accuracy, while any defects therein or deviations from correct form are minified in the workpiece. As a result of this method, it is possible to form a mandrel which produces fluted cone liners of very accurate form and which result in shaped charges capable of maximum compensation or nullification of the otherwise deleterious effects of spin upon the penetrating power of the ensuing jet. The result is that the superior accuracy and range of spinning projectiles may be effectively combined with the great penetrating power of shaped charges. Furthermore, the mandrels may be produced in quantity by the foregoing method and at relatively low cost. In addition, it is contemplated that equally accurate female members or dies 6 may be produced by electrodeposition upon the male members 1, by the process disclosed in co-pending application Pat. No. 2,643,221, filed Nov. 30, 1950, Ser. No. 198,471, in the names of Abner Brenner, Dwight E. Couch and Eugenia K. Williams, which process is also described in an article entitled The Electrodeposition of Phosphorous Alloys published in Plating a publication of the American Electroplaters Society, vol 37, Nos. 1 and 2, for January and February 1950, respectively. The process is also described in Research PaperRP 2061, January 1950, of the National Bureau of Standards, Washington, DC.

Having fully disclosed the invention, what I claim and desire to secure by Letters Patent is:

1. That method of cutting from a conical workpiece, a generally conical fluted mandrel having a plurality of equally angularly spaced radially offset surfaces connected by smooth canted surfaces, each canted surface and a contiguous offset surface constituting a segment, said method comprising, providing a master pattern shaped in correspondence with one segment only of the finished mandrel, mounting said pattern in operative relation with a cutter carried by a three-dimensional pantograph, traversing the stylus of the pantograph over the surface of said pattern to control the cutter to cut a single complete segment in the workpiece while holding the workpiece in fixed position, rotating the workpiece about its axis through the predetermined angle between successive offset surfaces, again traversing the pattern with the stylus of the pantograph to control the cutter to cut a second contiguous complete segment in the workpiece while again holding the workpiece in fixed position, and repeating the foregoing procedure until the entire surface of the workpiece has been cut.

2. That method of cutting from a conical workpiece, a generally conical fluted mandrel having a predetermined plurality of equally angularly spaced radially offset surfaces, each pair of contiguous offset surfaces being connected by a smooth regular canted surface, each canted surface and a contiguous offset surface constituting a segment, comprising, providing a master pattern formed as a single said segment only enlarged by a known scale factor, mounting said workpiece and pattern in operative relation with the cutting tool and stylus, respectively, of a three-dimensional pantograph attachment of a milling machine, set for a reduction factor equal to said scale factor, traversing the surface of said pattern with the stylus of said pantograph to cut a reduced complete segment in the workpiece while holding the workpiece in fixed position, rotating said workpiece on its axis by the angle between successive offset surfaces of the finished workpiece, again traversing the pattern to cut a second complete segment in the workpiece contiguous to the segment first cut while again holding the workpiece in fixed position, and repeating the procedure recited until the entire surface of the workpiece has been cut to form the aforesaid conical fluted mandrel.

References Cited UNITED STATES PATENTS 1,237,388 8/1917 Robertson et al. 33-23 2,066,372 1/1937 Tomalis 145-50.l 2,626,540 1/ 1953 Eserkaln 33-23 2,190,360 2/1940 Howard 266-23 2,433,564 12/1947 Keller -135 340,288 4/1886 Codling 90-62 732,154 6/1903 Barr 90-62 2,706,426 4/1955 Kelley 9013.7

ROBERT F. STAHL, Primary Examiner 

1. THAT METHOD OF CUTTING FROM A CONICAL WORKPIECE, A GENERALLY CONICAL FLUTED MANDREL HAVING A PLURALITY OF EQUALLY ANGULARLY SPACED RADIALLY OFFSET SURFACES CONNECTED BY SMOOTH CANTED SURFACES, EACH CANTED SURFACE AND A CONTIGUOUS OFFSET SURFACE CONSTITUTING A SEGMENT, SAID METHOD COMPRISING, PROVIDING A MASTER PATTERN SHAPED IN CORRESPONDENCE WITH ONE SEGMENT ONLY OF THE FINISHED MANDREL, MOUNTING SAID PATTERN IN OPERATIVE RELATION WITH A CUTTER CARRIED BY A THREE-DIMENSIONAL PANTOGRAPH, TRAVERSING THE STYLUS OF THE PANTOGRAPH OVER THE SURFACE OF SAID PATTERN TO CONTROL THE CUTTER TO CUT A SINGLE COMPLETE SEGMENT IN THE WORKPIECE WHILE HOLDING THE WORKPIECE IN FIXED POSITION, ROTATING THE WORKPIECE ABOUT ITS AXIS THROUGH THE PREDETERMINED ANGLE BETWEEN SUCCESSIVE OFFSET SURFACES, AGAIN TRAVERSING THE PATTERN WITH THE STYLUS OF THE PANTOGRAPH TO CONTROL THE CUTTER TO CUT A SECOND CONTIGUOUS COMPLETE SEGMENT IN THE WORKPIECE WHILE AGAIN HOLDING THE WORKPIECE IN FIXED POSITION, AND REPEATING THE FOREGOING PROCEDURE UNTIL THE ENTIRE SURFACE OF THE WORKPIECE HAS BEEN CUT. 